Although digital mobile phones have grown in spectacular fashion over the last few years, the growth in wireless data communication has also been impressive.

No doubt for the same reason, too: once you remove the need for a connecting cable, there's greater convenience as well as many more potential applications.

But the benefits of wireless data are by no means confined to high speed, wide bandwidth spread-spectrum technologies like Bluetooth and IEEE 802.11.

Fig.1: this is the circuit of the loop antenna version of the nRF401 evaluation kit. Three sizes of board are included, letting you determine optimum power output and current drain for a particular application.

A lot of short range applications can be served just as well by lower speed, lower bandwidth technology such as FSK (frequency shift keying, or "digital FM").

This can provide a very cost-effective solution for applications like alarm and security monitoring, home automation, remote control, short-range telemetry, automatic meter reading, toys and so on.

Putting this technology to work has been made particularly easy by Nordic VLSI ASA, a chip design and manufacturing company established in Norway in 1983.

In the last three years, Nordic has released a range of complete single-chip FSK data transceivers and transmitters, which are designed to operate on frequencies in the UHF bands allocated in most countries for either ISM (industrial, scientific and medical) or LIPD (low interference potential device) use.